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  <title>Document</title>
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  <script>
    function Star(uname,age){
      this.uname = uname;
      this.age = age;
    }
    var that;
    Star.prototype.sing = function(){
      console.log('我会唱歌');
      that = this;
    }
    var zsx = new Star('4xi',20);
    //1.在构造函数中，里面的this指向的是对象实例 zsx
    zsx.sing();
    console.log(that === zsx);

    //2.原型对象函数里面的this 指向的是 实例对象 zsx

  </script>
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